The α-subunit of the heterotrimeric G-protein affects jasmonate responses in Arabidopsis thaliana

Journal article

Heterotrimeric G-proteins have been implicated in having a role in many plant signalling pathways. To understand further the role of G-proteins, a preliminary experiment was performed to assess the impact of the Gα subunit loss-of-function mutation gpa1-1 on the Arabidopsis transcriptome. The analysis indicated that the Gα subunit may play a role in response to jasmonic acid (JA). Consistent with this, Gα mutants showed a reduced response to JA in inhibition of chlorophyll accumulation and root growth, whilst Gα gain-of-function plants overexpressing Gα showed the opposite phenotype. The levels of JA and related compounds were unaffected in the gpa1-1 mutant, as was autoregulation of the Allene Oxide Synthase (AOS) gene that encodes a key enzyme for JA biosynthesis. In contrast, further analyses using Gα loss- and gain-of-function Arabidopsis lines indicated that Gα positively modulates the expression of the Vegetative Storage Protein (VSP) gene. This indicates that the Gα subunit regulates a subset of JA-regulated genes defining a branch point in this signalling pathway in Arabidopsis. Further analysis of the impact of Gα loss of function upon the JA-regulated transcriptome using Arabidopsis full genome arrays indicated that up to 29% of genes that are >2-fold regulated by JA in the wild type are misregulated in the Gα mutant. This supports the observation that a significant proportion of, but not all, JA-regulated gene expression is mediated by Gα.

Authors: Okamoto, H; Gobel, C; Saunders, N; Feussner, I; Knight, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Journal of Experimental Botany
• Volume: 60
• Issue: 7
• Pages: 1991–2003
• Publication date: 2009-04-01
• Edition: Publisher's version
• DOI: 10.1093/jxb/erp060
• EISSN: 1460-2431
• ISSN: 0022-0957
• Language: English
• Subjects: Plant Sciences; Life Sciences; Molecular Plant Physiology